Ultra-violet sensitive paper



Patented Sept. 20, 1932 UNITED STATES PATENT OFFICE LEON W. EBERLIN, OF ROCHESTER, NEW YORK, ASSIGNOR TO EASTMAN KODAK COM- PANY, OF ROCHESTER, NEW YORK, A CORPORATION OF NEW YORK ULTRA-VIOLET SENSITIVE PAPER No Drawing. Application filed April 27,

This invention relates to photo-sensitive paper, the sensitivity of which lies chiefly in the ultra-violet.

It is desirable for certain actinometric purposes to have a light sensitive material which reacts to the near ultra-violet rays without being appreciably affected by the rest of the spectrum. Specifically, such a material may be used to demonstrate or dose the ultraviolet radiation of sunl ght and of various artificial light sources, particularly those used therapeutically. It is an object of this invention to produce such a paper.

Under the influence of ultra-violet l ght, ortho-nitrobenzaldehyde undergoes molecu lar rearrangement to orth-nitroso-benzoic acid. By using a suitable indicator with ortho-nitro-benzaldehyde,I have been able to produce a paper which is sensitive primarily to the ultra-violet and which has very little sensitivity in the visible spectrum. On 625- posure to ultra-violet light this paper gives within a short time a visible color change showing the transformation or rearrangement just described.

A test paper suitable for determining the intensity of ultra-violet light may be made by dipping sheets of unsized paper into a solution of Example I Ortho-nitro-benzaldehyde 1 gram Lacmoid 0.1 gram Ethyl alcohol 100 0.0.

Under the influence of ultra-violet this paper changes from blue to pink, and an exposure of about one minute is normally sufficient to produce a good color change.

Another suitable formula is the following:

Papers may be made with such solutions by either dipping or floating the sheets of paper upon the solution, then withdrawing and drying. Sized paper will, as a rule, not

1931. Serial No. 533,365.

as t will be evident that other substances are available for producing a satisfactory result;

What I claim as my invention and desire to secure by Letters Patent of the United States is:

1. A photo-sensitive sheet sensitive primarily to the ultra-violet comprising orthonitro-benzaldehyde. I

2. A photo-sensitive sheet sensitive primarily to the ultra-violet comprising orthonitro-benzaldehyde and an indicator.

3. A photo-sensitive sheet sensitive primarily to the ultra-violet comprising orthonitro-benzaldehyde and an indicator, which gives on exposure a visible color change.

Signed at Rochester, New York, this 20th day of April, 1931.

LEON W. EBERLIN. 

